Note: Descriptions are shown in the official language in which they were submitted.
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Title: SEAT BACK ADJUSTMENT MECHANISM FOR A CHAIR
FIELD OF THE INVENTION
This invention relates to a chair having a chair back member,
such as a pedestal-type office chair, wherein the inclination of the chair
back may be adjusted by actuating a fluid filled cylinder. The invention
also relates to an actuating mechanism for a chair having a chair back
member, wherein the inclination of the chair back member may be
actuated by a push button.
BACKGROUND OF THE INVENTION
Many chairs which are used in a commercial environment,
such as office chairs, have a height adjusting mechanism for permitting
the height of the chair to be raised or lowered to accommodate the user.
Typically, height adjustment mechanisms include a fluid filled cylinder,
such as a pneumatic cylinder (also known in the industry as gas dampers).
These chairs may also have a chair back whose inclination with respect to
the seat member may be adjusted.
Typically, office chairs comprise a wheeled base, the seat
portion of the chair (which may include a chair back) and a support leg
extending between the wheeled base and the seat portion. The height
adjustment mechanism may employ a telescoping pneumatic cylinder
which forms a part of, or may consist of, the support leg. These cylinders
have a valve release pin provided thereon. The cylinder is generally in a
locked condition but, when the valve release pin is depressed, the cylinder
is unlocked permitting it to telescopically extend upwardly or contract
downwardly.
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Various control linkages for height adjustment mechanisms
are known in the art. Examples of these include Kuhn et al (United States
Patent No. 5,069,496), Knapp (United States Patent No. 4,408,800), Slabon et
al (United States Patent No. 4,076,308), Wirges et al (United States Patent
No. 4,072,288), Knoblauch et al (United States Patent No. 4,373,692) and Lai
(United States Patent No. 5,222,783).
Numerous means have been used to control the inclination
of a chair back. These include various biasing means as well as the use of
pneumatic cylinders. See for example Meiller et al (United States Patent
No. 4,743,065), Lei et al (United States Patent No. 5,137,330), Kuhn et al
(United States Patent No. 5,069,496), Knapp (United States Patent No.
4,408,800), Simpson (United States Patent No. 4,681,369), Lai (United States
Patent No. 5,222,783), Slabon et al (United States Patent No. 4,076,308) and
Hiramatsu (United States Patent No. 3,284,135).
Generally, the pneumatic cylinder is adjusted by a leaver or
other mechanism which is positioned beneath the seat of the chair.
Accordingly, the user must extend their arm downwardly and then
transversely to a position underneath the seat to grasp the lever so that
they can actuate the height adjustment mechanism. This operation tends
to be difficult particularly if the chair has a large, bulky arm. Since the
cylinder is only operable when the valve release pin is depressed, the
operator must move the actuating lever to the open position and hold the
lever in the open position while setting the chair in the designated
position. As this may require the operator to bend or stoop over, it is
difficult to set the chair position accurately. This is also problematic if
the
operator has a back problem which prevents such movement.
Nelsen (United States Patent No. 4,595,237) discloses an
actuating control for a seat height adjustment mechanism. The
mechanism of Nelsen uses a pivotally mounted lever positioned on the
bottom of the seat member. Nelson still requires the user to extend their
arm downwardly beneath the seat to actuate the lever.
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SUMMARY OF THE INVENTION
In accordance with the instant invention, there is provided a
chair comprising a longitudinally extending seat member having a central
portion and opposed, transversly extending front and rear ends; a wheeled
base; a support member extending between the wheeled base and the
central portion of the seat member; a chair back member pivotally
mounted to the seat member for movement between an upright position
and a reclined position; an arm rest member having an actuating button
positioned in the arm rest member, the button being movable between a
first position and a second position; a fluid cylinder transversely offset
from the central portion having an actuating member and operatively
connected to the chair back member for adjustment of the inclination
thereof; and, a flexible cable having a first end connected to the button and
a second end operatively connected to the actuating member whereby,
when the button is moved from the first position to the second position,
the actuating member is actuated so that the inclination of the chair back
member may be adjusted and when the button is moved from the second
position to the first position, the inclination of the chair back member is
fixed.
In one embodiment, the cylinder has a telescopically
extendable section, a stationary section and a valve release member
moveable between a closed position in which the telescopically extendable
section is fixed in position relative to the stationary section and an open
position in which the telescopically extendable section is moveable
relative to the stationary section, the actuating member is operatively
connected to the valve release member and movable between a first
position, in which the valve release member is in the closed position, and
a second position, in which the valve release member is in the open
position whereby, when the button means is moved from the first
position to the second position, the valve release member is moved to the
open position so that the inclination of the chair back member may be
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adjusted and when the button means is moved from the second position
to the first position, the valve release member is moved to the closed
position so that the inclination of the chair back member is fixed.
In such an embodiment, one of the telescopically extendable
section and the stationary section is preferably mounted on the seat
member and the other of the telescopically extendable section and the
stationary section is pivotally connected to the chair back member. The
other of the telescopically extendable section and the stationary section
may be pivotally mounted on the chair back member. Alternately, the
chair back member may be mounted on an attachment member, the
attachment member is pivotally mounted on the seat member and the
other of the telescopically extendable section and the stationary section is
pivotally mounted on the attachment member.
In a further alternate embodiment, the actuating member
comprises an arm member pivotally mounted with respect to the valve
release member, the arm member having a moment arm of sufficient
length to permit the button means to move from the first position to the
second position by the force applied through a finger of the user when the
user is seated in the chair. Preferably, the actuating member has a base
member affixed proximate the valve release member, the arm member is
pivotally mounted to the base member and movement of the arm
member towards the base member causes the valve release member to
move to the open position.
In a further alternate embodiment, the chair comprises a seat
portion and a chair back member; the chair back member mounted on an
attachment member, the attachment member pivotally mounted on the
seat member; the seat portion including a fluid cylinder having
longitudinally extending telescopic first and second sections and a valve
release member, the first section connected to the seat portion and the
second section pivotally mounted on the attachment member, the valve
release member movable between a closed position in which the first and
second sections are fixed in position relative to each other and an open
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position in which the first and second sections are moveable relative to
each other; actuating means operatively connected to the valve release
member; button means positioned proximate the seat member and
movable between a first position and a second position; and, flexible cable
means having a first end connected to the button means and a second end
operatively connected to the actuator whereby, when the button means is
moved from the first position to the second position, the valve release
member is moved to the open position so that the inclination of the chair
back member of the chair may be adjusted and when the button means is
moved from the second position to the first position, the valve release
member is moved to the closed position so that the inclination of the chair
back member is then fixed.
Preferably, the button means is pushed inwardly (so as to
undergo a inward translational movement). The button may include cam
means for pulling the cable means when the button means is moved from
the first position to the second position such that, as the button means is
moved to the second position, the arm member pivots with respect to the
valve release member and moves the valve release member to the open
position.
Preferably, the chair has an arm member and the button is
located in the arm member. Thus, the user may operate the chair while in
a regular seated position. The user may merely push a button while sitting
in the chair and be able to easily move the chair back to the desired
inclination. Further, as will be apparent, a person whose back permits
25. them to have only limited movement may be able to easily set the chair
back to the desired inclination.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other advantages of the instant invention will be
more fully and completely understood by reference to the following
drawings of the preferred embodiment of the invention in which:
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Figure 1 is a perspective view of a chair according to the
instant invention;
Figure 2 is a schematic diagram of a height adjustment
mechanism according to the instant invention in which the height
adjustment mechanism is in the closed position;
Figure 3 is a schematic diagram of a height adjustment
mechanism according to the instant invention in which the height
adjustment mechanism is in the open position;
Figure 4 is an enlargement of detail B of Figure 2 showing the
button means in the closed position;
Figure 5 is an enlargement of detail D of Figure 3 showing the
button means in the open position;
Figure 6 is an enlargement of detail A of Figure 2 showing the
actuator means in the closed position;
Figure 7 is an enlargement of detail C of Figure 3 showing the
actuator means in the opened position;
Figure 8 is a perspective view of an actuator for the height
adjustment mechanism;
Figure 9 is a schematic diagram of a height adjustment
mechanism according to the instant invention when affixed to the seat
support member;
Figure 10 is a cross section along line 10 - 10 in Figure 9;
Figure 11 is a perspective view of the chair shown in Figure 1
wherein the spring support member for the seat member has been
removed;
Figure 12 is an enlargement of detail E of Figure 11;
Figure 13 is a side view of the chair of Figure 11 in which the
chair back is in an upright position; and,
Figure 14 is a side view of the chair of Figure 11 in which the
chair back is in an inclined position.
DESCRIPTION OF THE PREFERRED EMBODIMENT
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Referring to Figure 1, a pedestal chair is shown. For ease of
reference, the foam padding of the chair has been removed so that only the
frame members are visible. The chair.10 comprises seat member 12, chair
back member 14, wheeled base 16 and support leg 18 extending between
seat member 12 and wheeled base 16. Arms 20 are optionally provided on
opposite sides of seat member 12.
Chair back member 14 is affixed to seat member 12 by back
support member 22. Chair back member 14 is pivotally mounted with
respect to the seat member so that the angle of inclination of chair back 14
may be varied with respect to seat member 12. Chair back member 14 may
itself be pivotally mounted to seat member 12 (eg. by mounting the frame
of chair back member 14 to the frame of seat member 12). Preferably, as
shown in Figures 1 and 11, chair back member 14 is fixed to transverse rear
portion 164 that is itself pivotally mounted to seat member 12.
Seat member 12 may comprise frame 150 having longitudinal
side portions 152 and transverse front portion 154. Additional
reinforcement may be provided to frame 150 by transverse struts 156
which extend between longitudinal side portions 152. Transverse rear
portion 164 is pivotally mounted to longitudinal side portions 152 adjacent
the rear ends of longitudinal side portions 152.
Struts 156 may be affixed to the lower side of the longitudinal
side portions 152 by any means known in the art. For example, if side
portions 152 and struts 156 are made of metal, struts 156 may be welded or
bolted to side portions 152. In the preferred embodiment of Figures 1 and
11, each strut 156 has descending portions 158 which are connected by
horizontal portion 160. Horizontal portion 160 provides a mounting
platform for support leg 18 which is positioned below seat member 12.
As shown in Figures 1 and 11, chair back member 14 has a
mounting plate 162. The upper portion of back support member 22 is
attached to mounting plate 162. For example, if back support member 22
and mounting plate 162 are made of metal, back support member 22 may
be welded or bolted to mounting plate 162. Alternately, back support
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member 22 may be slideably received in mounting plate 162 so that the
height of chair back member 14 may be adjusted with respect to seat
member 12. As shown in Figures 1 and 11, back support member 22 may be
received in a opening in mounting plate 162 which is dimensioned to
fixedly hold back support member 22 in place. Similarly, the lower portion
of back support member 22 is attached to transverse rear portion 164. For
example, if back support member 22 and transverse rear portion 164 are
made of metal, back support member 22 may be welded or bolted to
transverse rear portion 164.
Transverse rear portion 164 is preferably pivotally secured to
the rear portions of longitudinal side portions 152 by pivot means 166.
Transverse rear portion 164 may have descending end portions 168 and
central horizontal portion 170. Pivot means 166 may be any means known
in the art. For example, pivot means 166 may comprise a bolt having a
head (positioned on the inner surface of descending portion 168), a
longitudinally extending body portion (extending through descending
portion 168) and an end (positioned in longitudinal side portion 152) to
which a bolt is attached. A spacer 172 may be placed over a portion of the
longitudinally extending body portion of the bolt. Transverse rear portion
164 may accordingly be pivotally mounted between the bolt and spacer 172.
Accordingly, chair back member 14 is fixed in position with respect to
transverse member 164 and pivots with respect to seat member 12 as
transverse member 164 pivots. As will be appreciated, by affixing chair back
member 14 to member 164 that is pivotally mounted to seat member 12,
member 164 defines a moment arm which levers the force that is applied
to move seat back member 14.
Support leg 18 comprises a telescoping cylinder having upper
section 24, a lower section 26 and a valve release pin 28. The cylinder may
be a fluid cylinder and is preferably a pneumatic cylinder. The cylinders are
generally known in the art and have two internal chambers (now shown).
When the valve release pin is in the closed position as shown in Figure 2,
the chambers are isolated from each other. Accordingly, the cylinder, and
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therefore the height of the chair, is locked at a predetermined position.
When the valve release pin is moved to the open position as shown in
Figure 3, the two chambers are allowed to communicate permitting upper
section 24 to move upwardly or downwardly with respect to lower section
24. Thus the height of the chair may be adjusted.
Typically, when the valve is released, the cylinder is designed
to cause upward movement of seat member 12 when the seat is
unoccupied or at least a significant portion of the user's weight is removed
therefrom. By permitting seat member 12 to move upwardly under this
pressure, or applying downward pressure (e.g. applying a part of the user's
weight to seat member 12) the height of the chair may be decreased. When
valve release pin 28 is moved to the closed position, then the
communication between the chambers is terminated and the position of
upper section 24 with respect to lower section 26 is fixed.
Generally, valve release pin 28 is positioned on the top of
upper section 24 (see for example Figure 2). However, as will be discussed
more fully below, due to the construction of the actuator for the height
adjustment mechanism of the instant invention, the valve release pin
may be positioned at any desired location on the cylinder.
As shown in Figures 9 and 10, upper section 24 is received in
bushing 150 which has an opening 152. Bushing 150 is a tapered bushing.
Similarly, the upper portion of upper section 24 is tapered. Accordingly,
upper section 24 is mounted in bushing 152 by means of a taper fit as is
known in the art. Bushing 150 is affixed to plate 154. Plate 154 has upraised
flanges 156 which have a plurality of openings 158 provided therein. Seat
member 12 may be affixed to plate 154 by means of screws passing through
openings 158 and into the bottom portion of seat member 12.
Typically, pedestal type chairs may include additional
mechanisms to adjust the position of the chair for the comfort of the user.
These include means for tilting seat member 12 with respect to support leg
18. These devices may be mounted, as is normal in the trade, below the
seat member. Many of these devices are known in the art and some are
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referred to in the patents referred to above in the portion of this
specification entitled "Background of the Invention". As will be
appreciated during the discussion of the instant actuating member, the
actuating member of this invention may be used in a chair that contains
one or more of these devices.
Referring to Figures 2 and 3, actuating mechanism 30 of the
instant invention is shown isolated from chair 10. Actuating means 30
comprises actuator 32, button means 36 and cable 34 extending between
actuator 32 and button means 36.
As valve release pin 28 is mounted on top of upper section 24
of the cylinder, actuator 32 is also mounted thereon. Actuator 32 has a
lower plate 38, upper pivoting arm 40 and pivot axle 42. Pivot axle 42 is
mounted between a pair of flanges 44 which extend upwardly from plate
38. Plate 38 is positioned on top of upper section 24 of the cylinder and
provides a fixed mount for pivot axle 42. As will be appreciated, plate 38
may be of any particular shape and any particular orientation provided
that a fixed mount is provided for pivot axle 42.
In particular, it is appreciated that seat member 12 must be
fixed on top of section 24 and that additional mechanisms, including a
back angle adjustment mechanism and a tilt mechanism for seat member
12 may be provided or that a different method may be used to affix upper
section 24 to seat member 12. The addition of these mechanisms may
require a different orientation and configuration for plate 38.
Referring to Figures 6 and 7, pivoting arm 40 has a first
portion 46, second portion 48 and a third portion 50. First portion 46 is
pivotally mounted for rotation about pivot axle 42. Second portion is
adapted to be affixed to cable 14. Third portion 50 is adapted for contacting
valve 28.
Referring to Figure 8, actuator 32 is shown in more detail. As
can be seen in this view, plate 38 comprises a longitudinally extending
generally flat member 39 having a central opening designated by reference
numeral 60. When actuator 32 is positioned on top of upper section 24 of
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the cylinder, pin 28 extends upwardly through opening 60 and contacts the
lower surface of third portion 50. Flanges 44 extend upwardly from
generally flat member 39. First portion 46 of pivot arm 40 wraps around
pivot axle 42 so that arm 40 may pivot upwardly and downwardly with
respect to plate 38.
Second portion 48 of pivot arm 40 has a cable retaining
opening 66 provided therein. Plate 38 has a descending portion 68 to match
that of arm 40. Opening 70 is provided in the front thereof.
Reference will now be made to Figures 6 and 7 which show a
schematic of actuator 32 positioned on top of the cylinder with the cable
attached. Cable 34 may be made of a variety of materials which may accept
a tensional force without breaking, e.g. braided wire. Cable 34 may be
sheathed in a plastic or like housing 72 to permit the smooth movement
of cable 34 therein. Cable 34 is provided with enlarged end 74. Housing 74
has shoulder members 76 which abut against lower surface 78 of
descending portion 68. Cable 34 passes through openings 66 and 70.
Enlarged end 74 is retained on upper surface 80 of second portion 48, such
as by providing a recess in which enlarged end 74 is seated, while
permitting cable 34 to pass through opening 66 and 70.
Button means 100 is shown in Figures 4 and 5. Button means
100 comprises button 102 and transversely extending member 104.
Transversely extending member 104 extends outwardly from rear surface
106 of button 102. Transversely extending member 104 extends through an
opening (see Figure 10) in housing 108. Transversely extending member
104 has distal end 110 on which is provided disk member 112. Disk
member 112 has a larger diameter than transversely extending member
104 so as to retain button 102 within housing 108.
Housing 108 has a first arm 114 and a second arm 116. Cam
member 118 is pivotally mounted on pivot axle 115 which is located at the
distal end of first arm 114. As discussed above with respect to actuator 32,
cable 34 has a shoulder member 76 and the end of cable 34 connected to
button means 100 has an enlarged end 74. Cam member 118 is provided
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with an opening (see Figure 10) through which cable 34 passes. Enlarged
end 74 is retained against surface 120 of cam member 118 such as by
providing a recess in which enlarged end 74 is seated. Second arm member
116 has an opening through which cable 34 passes. Shoulder
member 76 abuts against lower surface 122 of second arm 116.
It will be appreciated that cable 34 may be retained in first
portion 48 and cam member 118 by any means known in the art. Cable 34
may be fixedly attached thereto, (e.g. by welding, gluing or the like).
Alternately, cable 34 may be removably connected thereto for ease of repair
in case cable 34 should break.
Referring to Figures 2 and 3, the operation of the actuating
means will now be described. Referring first to Figure 2, valve release pin
28 is shown in the closed position. In this position, pin 28 is in its raised
position. Due to the construction of the cylinder, pin 28 is biased into this
position so that the cylinder will not be prematurely activated. The
pressure exerted by pin 28 against arm 40 causes arm 40 to be maintained
in a raised position with respect to plate 38. This force on arm 40 is
transmitted through cable 34 and therefore maintains cam member 118 in
the position shown in Figure 2. Arm 124 of cam member 118 transmits
this force outwardly through transversely extending member 104 to button
102.
When the user wishes to adjust the height of the chair, they
push inwardly on button 102 with, for example, their thumb. This causes
button 102 to move to the position shown in Figure 3. When button 102 is
pushed inwardly, transversely extending member 104 pushes on arm 124
of cam member 118 moving cam member 118 to the position shown in
Figure 3. This movement of cam member 118 causes cable 34 to draw arm
40 of actuator 32 downwardly towards plate 38 of actuator 32. By this
movement, valve pin 28 is forced downwardly to the open position thus
permitting upper section 24 to telescope either upwardly or downwardly
with respect to lower section 26. When the chair has been moved to the
desired position, the user releases button 102 permitting valve 28 to move
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arm 40 to the raised position shown in Figure 3 thus closing the valve. In
this position, the chair is once again fixed at a particular, desired height.
Referring to Figure 6, it will be appreciated that arm 40
provides a moment arm to reduce the pressure which must be exerted by
the user to move valve release pin 28 from the closed position to the open
position. In particular, the distance between pivot pin 28 and cable 34,
referred to by reference numeral B in Figure 6, provides a moment arm
which is substantially longer in the distance between pivot axle 42 and
valve release pin 28 (referred to by reference numeral A). By varying the
length of moment arm B with respect to A, the amount of force which
must be applied, and the distance through which cable 34 must travel, may
be adjusted. Preferably, the length of movement arm B with respect to A,
and its configuration, are sufficient to permit button 102 to be depressed
when a relatively low force is applied by the user, e.g. that pressure which
may be applied by the average person. If moment arm B is too long or the
distance which must be travelled by second portion 48 is too short, then
the height adjustment means may be accidentally actuated by the user by
merely brushing against button 102. The ratio of the distances B to A
preferably varies from about 1.5:1 to about 5:1, more preferably from about
2:1 to about 4:1 and, most preferably, the ratio is about 3:1.
By constructing actuator 32 according to this invention, the
amount of pressure directed downwardly on valve pin 28 by pivot arm 40
may be substantially greater than the pressure required to depress button
102. Preferably, a pressure of from about 10 to about 20, more preferably
from about 15 to about 20 lbs., is required to move valve release pin 28 to
the open position. In such a case, the pressure required to move button 102
may vary from about 5 to about 10 lbs. and, more preferably, is about 8 lbs.
If the pressure required to move button 102 is less than about 5 lbs., then
button 102 may be accidentally actuated by the user brushing against it. If
the pressure is greater than about 10 lbs., then the pressure may be too
great for many users to easily actuate the height adjustment mechanism. It
has been found that a pressure of about 8 lbs. is optimal.
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Generally, the arms of chairs are relatively thin. Thus, to fit
button means 100 in the arm of a chair, button 102 generally has a
relatively short stroke between the released position shown in Figure 4
and the depressed position shown in Figure 5. Preferably, the distance
travelled by button 102 may be up to about 3/4 of an inch but, preferably is
about 5/8 of an inch. Correspondingly, the distance travelled by third
portion 50 is preferably about 1 /4 of an inch. Thus, due to the length of
moment arm B, the ratio of the distance travelled by button 102 to third
portion 50 is about 2:1. This permits about a corresponding increase in the
magnitude of the force applied by third portion 50 to valve release pin 28.
As shown in Figures 11, 13 and 14, tilt adjustment
mechanism 180 is mounted offset to one side, and in the plane of, seat
member 12. Mechanism 180 comprises motion control fluid cylinder 182
having stationary housing 184, telescopically expandable piston 186
mounted therein and valve release pin 188. Motion control fluid cylinder
182 is preferably fixedly mounted to the forward portion of seat member 12
by means of forward mount 190 and, preferably, pivotally mounted to the
rear of seat member 12 by rearward pivot mount 192.
Motion control fluid cylinder 72 maybe a fluid cylinder and is
preferably filled with a non-compressible fluid (e.g. oil). As is known in
the art, motion control fluid cylinder 182 has two internal chambers which
are isolated from each other by means of a valve (not shown). When the
valve is opened, fluid may flow from one chamber to the other thus
allowing telescopically expandable piston 186 to expand forwardly, or
contract rearwardly, with respect to stationary housing 184. When valve
release pin 188 is in the closed position, then the valve is closed and the
two chambers are isolated from each other so that piston 186 is fixed in
position with respect to housing 184. Accordingly, the inclination of chair
back member 14 is fixed in position when valve release pin 188 is in the
closed position. When valve release pin 188 is moved to the open
position, then the valve is open and the two chambers are allowed to
communicate permitting piston 186 to expand outwardly from housing
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184 or to contract inwardly into housing 184 so that the inclination chair
back member 14 may be adjusted either forwardly or rearwardly.
Forward mount 190 may comprise a flange which descends
from the lower surface of horizontal portion 160. The forward end of
piston 186 extends through an opening in the flange and is fixedly
mounted thereto. Piston 186 may be fixedly mounted thereto by any means
known in the art. Therefore, any movement of piston 186 with respect to
housing 184 causes housing 184 to move rearwardly.
Rearward pivot mount 192 may comprise flange 194 and
extension arms 196. Referring to Figures 13 and 14, flange 194 extends
forwardly from the lower surface of horizontal portion 170. Extension
arms 196 extend rearwardly from housing 184. Extension arms 196 may be
pivotally connected to flange 194 by any means known in the art. As
shown in Figures 11 and 12, extension arms 196 are pivotally connected to
flange 194 by means of bolt 198 and screw 200.
Actuator 210 is mounted on the forward portion of piston 186
at a position forward of mount 190. Actuator 210 has a stationary arm 212
and pivoting arm 214 which is pivotally connected to stationary arm 212 by
pivot pin 216. Stationary arm 212 may be affixed to piston 186 by any
means known in the art that provides a fixed amount for pivot pin 216. As
will be appreciated, stationary arm 212 may be of any particular shape that
provides a fixed mount for pivot pin 216. Pivoting arm 214 has inner
surface 218.
The distal end of arm 212 from pivot pin 216 is provided with
opening 220. Similarly, the distal end of pivoting arm 214 from pivot pin
216 is provided with an opening (not shown). As discussed above with
respect to the height adjustment actuator, cable 114 comprises, e.g. a
braided wire 34, which is held within a plastic like housing 72 to permit
smooth movement of wire 34 therein. Wire 34 is provided with enlarged
end 120. Cable 114 is provided with shoulder member 116 which abuts
against stationary arm 212. Wire 34 passes through the openings in arms
212 and 214. Enlarged end 120 is retained on outer surface 224 of pivoting
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arm 214, such as by providing a recess in which enlarged end 120 is seated,
while permitting wire 34 to pass through the openings in arms 212 and
214.
An opening is provided in stationary arm 212 so that, as
pivoting arm 214 moves towards stationary arm 212, release pin 188 is
moved from the closed position (in which piston 186 is fixed in position
with respect to housing 184) to the open position (in which piston 186 may
move with respect to housing 184). To this end, as shown in Figure 12,
valve release pin may extend outwardly through stationary arm 212. Inner
surface 218 of pivoting arm 214 may be flat so that as arm 214 pivots
towards stationary arm 212, valve release pin 188 is depressed into housing
184 thus opening the valve. Alternately, as shown in Figure 12, it will be
appreciated that protrusion 226 or other button means may be provided on
inner surface 218 to contact valve release pin 188 and that valve release
pin 188 may be recessed within stationary arm 212 if the button means is of
sufficient size.
As with the height adjustment means, wire 34 is affixed to a
second button means l00 as is shown in Figures 4 and 5. The button means
100 which operates actuator 210 may be positioned beside the button
means 100 which operates actuator 32. Alternately, the button means 100
which operates actuator 210 may be positioned in the other arm 20 from
the button means 100 which operates actuator 32.
The operation of actuator 210 will now be described. Valve
release pin 188 is biased to the closed position (the raised position as
shown herein). Due to the construction of the cylinder, valve release pin
188 is biased into this position so that cylinder 72 will not be prematurely
actuated. The pressure exerted by valve release pin 188 against arm 214
causes arm 214 to be maintained in the distal position with respect to
stationary arm 212. Optionally, spring means 232, which extends between
arms 212 and 214, may be provided to assist in maintaining arm 214 in the
distal position. This force upon arm 214 is transmitted through wire 34
and therefore retains cam member 118 in the position shown in Figure 4.
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Arm 124 of cam member 118 transmits this force outwardly through
transversely extending member 104 to button 102 so that button 102 is in
the raised position shown in Figure 6.
When the user wishes to adjust the inclination of chair back
14 chair, they push inwardly on button 102 with, for example, their thumb.
This causes button 102 to move to the recessed (open) position shown in
Figure 5. When button 102 is pushed inwardly, transversely extending
member 104 pushes on arm 124 of cam member 118 moving cam member
118 to the position shown in Figure 5. This movement of cam member
118 causes cable 34 to draw arm 214 towards stationary arm 212. By this
movement, valve release pin 188 is forced inwardly into the cylinder thus
permitting piston 186 to telescope either inwardly or outwardly with
respect to housing 184. When chair back member 14 has been moved to
the desired position, the user releases button 102 permitting valve release
pin 188 to move arm 214 to the distal (closed) position thus closing the
valve. In this position, the inclination of the chair back is once again fixed
at the desired inclination. In order to bias, or assist in biasing chair back
14
to an upright position, spring 230 may be placed on piston 186. Spring 230
imparts a rearward force to housing 184. Thus, when valve release pin 188
is in the open position and the worker does not apply any force to chair
back 14, chair back 14 will move to an upright position.
Referring to Figure 12, it will be appreciated that arm 214
provides a moment arm to reduce the pressure which must be exerted by
the user to move valve release pin 188 from the closed position to the
25. open position. In particular, the distance between valve release pin 188
and wire 34, referred to by reference numeral B in Figure 12, provides a
moment arm which is substantially longer than the distance between
pivot pin 216 and valve release pin 188, referred to by reference numeral
A. By varying the length of moment arm B with respect to A, the amount
of force which must be applied, and the distance through which wire 34
must travel, may be adjusted. Preferably, the length of moment arm B
with respect to A, and it's configuration, are sufficient to permit button 102
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to be depressed when a relatively low force is applied by the user, e.g. that
pressure which may be applied through a finger by the average person. If
moment arm B is too long, or the distance which must be travelled by arm
214 is too short, then the adjustment mechanism may be accidentally
actuated by the user by merely brushing against button 102. The ratio of
the distances B to A preferably varies from about 2:1 to about 3:1 and more
preferably about 2.5:1.
By constructing actuator 2l0 according to this invention, the
amount of pressure directed on the valve release pin 188 by pivot arm 214
may be substantially greater than the pressure required to depress button
102. Preferably, a pressure of from abut 10 to about 20 lbs., more preferably
from about 15 to about 20 lbs., is required to move valve release pin 188 to
the open position. In such a case, the pressure required to move button
102 may vary from about 5 to about 10 lbs. and, more preferably, is about 8
lbs. If the pressure required to move button 102 is less than about 5
pounds, then button 102 may be accidentally actuated by the user brushing
against it. If the pressure is greater than about 10 pounds, then the
pressure may be too great for many users to easily actuate the height
adjustment mechanism. It has been found that the pressure from about 8
pounds is optimal.
It will be appreciated by those skilled in the art that various
modifications to actuator 32 may be permissible. For example, if the
cylinder was actuated by the outward (upward) movement of valve release
pin 28, then, button means 102 could be designed to release tension in
cable 34, permitting the expansion outwardly of valve release pin 28, as
opposed to providing a tensional force thereto as shown herein. Further,
as will be appreciated by those skilled in the art, the exact configuration
and orientation of plate 38 may be adjusted so long as a fixed mount is
provided for pivot axle 42. Further, the exact configuration and orientation
of arm 40 may be varied. A similar modification could be made to actuator
210.
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In an alternate embodiment, button 102 may be designed so as
to be capable of being locked in both the open position and the closed
position. Thus, when button 102 is in the raised, closed position as shown
in Figure 4, the inclination of chair back 14 may be locked in an upright
position or in an inclined position with respect to seat member 12.
Alternately, when button 102 is locked in the recessed, open position as
shown in Figure 5, chair back 14 may be rocked backwards andlor forwards
with respect to the seat member 12.
